I did some testing with the onboard IDE port, and definetively it's not possible to connect a slave device of any kind. Instead, I found in my stash a 8 GB CF card that works as HD on it! Perfectly compatible, installed OnTrack Disk Manager just fine, and it's tock solid. Apparently, it's a card problem, not an adapter's one.

I also found a 16 bit sound card with an IDE port that works on a 286: it's an ESS 1868 PnP. It also works in Windows 3.1 (unlike the SB16, which requires a 386), but the driver is buggy: every time Windows starts, it changes its own config to use DMA 255
If anyone has the same problem, check system.ini, section [auddrive.drv], value DMAChannelWave2.
CD and CFs works nice on it... however, SATA or SD adapters do not, they even prevent the PCS from booting

Actually I couldn't play 16 bit wave files, apparently I don't have enough RAM. Speaking of which, I have 1 MB at the moment, and I want to install all 4 MBs, but most of the SIMMs I see have 3 chips. Have you tried those? If I remember well, my old one had the 9 chips ones, and I read the 3-chips needs to be explicitly supported.
On the other hand, the puny 256 kB SIMMs currently installed have 3 chips (I also just discovered that there are 512 kB on board, I thought these were 512 kB SIMMs but they don't exist at all).
There is also the 2 chips version, which doesn't have parity, MAYBE they will work?
And what about FPM modules? Choices, choices...

And last, the two different mainboards. Take a look at this shot from the user's guide: it depicts the installation of the coprocessor. The manual says to check which model of the board you have, and A is the one I have (with the Headland chipset), and from the photos I see online the B model is the TI one.
Seems like there always were 2 models. How strange.
Uhm, perhaps you should reflect that in the patch

Re: [patch] Systems from the first Olivetti PCS series

Non-parity modules have an even number of chips and were used mostly on 68k machines.

All SIMM's with 3 or 9 chips have parity and should work on any x86 board, at least 256KB and 1MB ones.
4MB and 16MB may be too big for some configurations with early chipsets supporting only up to 8MB (or less)

30 pin SIMMs were all of FPM type like the first 72 pin SIMMs, I think EDO wast first introduced with/for the Intel Triton chipsets.

On that picture of the manual the SIMM's are placed starting from the power connector side but sometimes you must place them in the opposite order when not using all slots.

Re: [patch] Systems from the first Olivetti PCS series

Non-parity modules have an even number of chips and were used mostly on 68k machines.

All SIMM's with 3 or 9 chips have parity and should work on any x86 board, at least 256KB and 1MB ones.

30 pin SIMMs were all of FPM type like the first 72 pin SIMMs, I think EDO wast first introduced with/for the Intel Triton chipsets.

Never mind what I said... my SIMMs have 2 chips. Also, the onboard memory has no parity chip I could see.
The chips are MCM514256, 256k x 4 "FPM capable" as the datasheet says. I did a bit more research (there's a lot of confusion out there) and it seems like FPM is always backward compatible; practically all SIMMs were FPM (even though older chipsets do not use this feature).
At this point, I think every module should be compatible with this machine. The extra chip for parity shouldn't be a problem.

On that picture of the manual the SIMM's are placed starting from the power connector side but sometimes you must place them in the opposite order when not using all slots.

The modules in my machines were always in the slots close to the power. The manual says that in order to upgrade from 1 MB to 2 MB you have to remove the factory modules and put the 1 MB ones in those slots (and move the jumper, probably to disable the onboard memory); and to upgrade from 2 MB to 4 you have to put two extra modules in the other two slots. No other configuration is described.

Well, I'm off buying that RAM. I'm tired of out of memory errors in Windows

After that: networking!

Re: [patch] Systems from the first Olivetti PCS series

Posted: Tue 23 Oct, 2018 4:13 pm

by ruben_balea

It's interesting, I never tried non parity modules because my PCS386SX was upgraded when my Olivetti dealer was already making their own generic computers and they fitted 8x1MB Samsung parity SIMMs and really I don't know what it has before.
Olivetti OEM modules could be made by Samsung too but I'd expect to see some custom labelling and those had only the same label found on aftermarket Samsung modules.

Parity chip is another RAM chip with the capacity in bits as the module has in bytes so we can assume that a module with parity would be at least 11% more expensive.
Perhaps parity test pass always when there aren't parity chips on the modules or the chipset has some way to make its own internal checks witouth additional chips

Re: [patch] Systems from the first Olivetti PCS series

Posted: Wed 24 Oct, 2018 10:54 am

by biffuz

I just spoke with a guy who did board repairs in the '90s, and he said that some 286 and 386SX boards with onboard memory will use such memory as parity bank when external memory is used

Re: [patch] Systems from the first Olivetti PCS series

Posted: Wed 24 Oct, 2018 2:54 pm

by ruben_balea

Last night while looking for another thing I found an original 256KB module from my PCS386SX and it's non parity and 2 chips type too.
I was already convinced the store had not returned me those after the upgrade but it was under the bottom flap of a carton box so the other 3 may been lost by the same way

Re: [patch] Systems from the first Olivetti PCS series

Posted: Sun 04 Nov, 2018 11:05 pm

by biffuz

Well, here I am... I got 4 sticks of RAM. It recognizes them and it seems to work, but it's very unstable. Even DOS hangs

They are 4x Samsung KMM591000CN-7. The chips are 2x KM44C1000CJ-7 + 1x KM41C1000CJ-7. They seem absolutely fine.
They are rated for 70 ns. The onboard chips for 100, the original SIMMs for 80, so I don't think it's a speed issue.

Obviuosly I tried the usual swapping, trying only 2 at a time (all possible combinations), etc. I also tried to cover the parity pins, no difference.
CHECKIT passes long tests just fine, BUT sometimes it hangs afterwards.
Also, it doesn't test extended memory at all, only the base 640k. It seems to think it's in use. Any other memory test program for a 286 out there?

I don't want to buy random modules hoping they work... any suggestion appreciated!

On that picture of the manual the SIMM's are placed starting from the power connector side but sometimes you must place them in the opposite order when not using all slots.

The modules in my machines were always in the slots close to the power. The manual says that in order to upgrade from 1 MB to 2 MB you have to remove the factory modules and put the 1 MB ones in those slots (and move the jumper, probably to disable the onboard memory); and to upgrade from 2 MB to 4 you have to put two extra modules in the other two slots. No other configuration is described.

Never mind what I said... again
You were right, the first two 1 MB modules go on the sockets away from the PSU.